Facile Two‐Step Synthesis of 1,10‐Phenanthroline‐Derived Polyaza[7]helicenes with High Fluorescence and CPL Efficiency

Abstract

Abstract A facile two‐step synthesis of aza[7]helicenes possessing a 6‐5‐6‐6‐6‐5‐6 skeleton from commercially available 2,9‐dichloro‐1,10‐phenanthroline via double amination with aniline derivatives followed by hypervalent iodine reagent‐mediated intramolecular double‐NH/CH couplings was developed. Single‐crystal X‐ray analyses of the helicenes revealed unique structures, including both a significantly twisted center and planar terminals of the skeleton. The azahelicenes show high fluorescent quantum yields ( Φ s) under both neutral ( Φ : 0.25–0.55) and acidic conditions ( Φ : up to 0.80). An enantiomerically pure aza[7]helicene showed high circularly polarized luminescence (CPL) activity under both neutral and acidic conditions ( g lum : up to 0.009).